Rhythm Disturbances

Brugada Syndrome

- Congenital disorder - Incomplete RBBB + ST elevations in V1-V3 - At risk for SCD from v-fib/v-tach Treatment: AICD

Second degree heart block: type II

- Consistent PR intervals but not every P has a QRS - Usually due to a distal infranodal AV block - Wide QRS Treatment: regardless of symptoms - needs permanent pacemaker implantation to prevent shift into 3rd degree complete heart block

Long QT syndrome

- Genetic condition causes QT to extend past half the RR interval - May be caused/worsened by certain medications Treatments: - d/c offending drug - beta blockers - fast pacing - AICD

Second degree heart block: type I

- Progressively longer PR intervals with a dropped QRS - If hemodynamically stable, no treatment needed but should monitor 2x/year If symptomatic: - treat the underlying condition - consider permanent pacemaker implantation

Left Bundle Branch Block

- QRS > 0.12s - Large R waves in leads I & V6 - Deep S wave in V1 - Common after MI - Causes: HTN, fibrosis, cardiomyopathies Treat as STEMI until proven otherwise

Right Bundle Branch Block

- Widened QRS > 0.12s - RSR' (bunny ears) in V1 - Caused by strain on RV (cor pulmonale, PE, ASD)

First degree heart block

AV block that causes a delay in signal between atria and ventricles (*long PR interval*) - should monitor - usually hemodynamically stable and does not require tx If symptomatic: - treat the underlying condition - consider permanent pacemaker implantation

Wolff-Parkinson-White Syndrome (WPW)

Accessory pathway (bundle of Kent) between atria & ventricles causes early depolarization of ventricles --> sudden on-off tachycardia - Early QRS complex - Short PR interval - Delta wave - Fatal if present w/ A-fib - Concerning if signal travels backwards to atria and causes AVRT Treatment: - Adenosine, *vagal*, non-DHP *CCB* can reset the pattern - *Ablation* of accessory pathway

Non-sustained Ventricular Tachycardia

At least 3 PVCs in a row: - Benign if there's no comorbid CVD - Poor prognostic factor if there's CVD Treatment: - Beta blockers or non-DHP CCBs - Last resort: antiarrhythmics (amiodarone)

Third degree heart block

Cardiac emergency: P waves and QRS waves have their own rhythms, but RR is consistent - Bradycardic Treatment: - temporary transvenous pacemaker if asymptomatic but will require permanent pacemaker

Ventricular fibrillation

Disorganized, ineffective twitching of the ventricles, resulting in no blood flow and a state of cardiac arrest. *Defibrillate ASAP!*

Sinus Node Dysfunction / Sick Sinus Syndrome / Tachy-Brady

Dysfunctional SA node causes alternating periods of bradycardia & tachycardia *Symptoms*: - Fatigue (from bradycardia -> slow HR) - Lightheadedness (from tachycardia -> reduced CO) - Palpitations - Pre/Syncope *Causes*: hx of myocarditis, atrial stretch, valve disease, anything that disturbs the SA node *Treatment:* - Pacer to treat bradycardia - Beta blockers prn to treat tachycardia

Ventricular ectopy

Extra heartbeat (premature ventricular contraction, PVC) occurs before the beat triggered by the heart's normal function; can reduce CO - Rare: 1-2/min - Occasional: 2-3/min - Frequent: 6/min Origin of beat: - Unifocal: usually benign - Multifocal: usually due to ischemia Treatment: - Avoid caffeine, drugs, alcohol - Beta blockers or CCBs

AV nodal reentrant tachycardia

Fast, regular ventricular rhythm caused by cycle of electrical activity within the AV node; P waves are hidden in QRS complexes *Signs*: inverted P wave in lead II and upright P wave in lead V1 Cause: slow anterograde track and fast retrograde track in AV node Treatments: - Adenosine and vagal maneuvers will break the pattern - Beta blockers or CCBs - Ablation, may need permanent pacemaker

Paroxysmal Supraventricular Tachycardia

Periods of normal sinus rhythm and sudden tachycardia w/ regular, narrow QRS complex *Symptoms:* - palpitations - dizziness/lightheadedness *Causes*: AVRT, AVNRT, atrial tachycardia *Treatment*: - Vagal stimulation or adenosine will break the pattern - Ablation of AV node & pacemaker

Atrial tachycardia

Rapid heartbeat originating from atria outside of SA node --> abnormal P waves & narrow QRS complex Treatment: - Adenosine or vagal will *slow* the rhythm - *Beta blockers, non-DHP CCBs, antiarrhythmics*

AV reentrant tachycardia (AVRT)

Signal from ventricles travel up through an accessory pathway to the atria before the SA node can send out its own signal, causing tachycardia

Torsades de pointes

Treat w/ IV Mg and defibrillation

Ventricular tachycardia (V-tach)

Very rapid heartbeat originating within the ventricles that doesn't allow ample time for heart to fill w/ blood Treatments: - If stable -> amiodarone - If unstable -> synchronized cardioversion - If pulseless -> defibrillation